The present invention relates to a process for the treatment of lead sulphide with an aqueous solution of sulphur dioxide. In a particular embodiment the present invention relates to a process for the recovery of lead from lead sulphide.
Techniques for the treatment of lead sulphide are known. For example, lead sulphide may be treated by a pyrometallurgical process involving sintering the lead sulphide to remove sulphur as sulphur dioxide. Elemental lead is then produced by reduction of the sintered material, and the lead so obtained may be processed further by known methods. However, sulphur dioxide is produced in the sintering process and this gas may be the source of a potential pollution problem. The sulphur dioxide may be used in another process or converted to sulphur by treating the sulphur dioxide with hydrogen sulphide, to sulphuric acid for subsequent sale or disposal, or the sulphur dioxide may be sold as such. The way in which the sulphur dioxide is utilized may be an important factor in the economics of processes for the recovery of lead from lead sulphide. Lead sulphide may also be treated with sulphuric acid in the presence of oxygen at pressures above atmospheric pressure to produce lead sulphate. Lead may then be obtained by treating the lead sulphate in a pyrometallurgical process.
The known techniques for the treatment of lead sulphide and lead sulphate are capable of improvement especially with regard to the potential pollution problems associated with such techniques. Also, techniques are known for the reaction of iron sulphides with sulphur dioxide to obtain sulphur as in Canadian Patent No. 926,087 - Kunda, issued May 15, 1973, but such techniques do not utilize lead sulphides.